The shape of the lesson
By the end of the lesson, learners can
- Feel the force between poles: Bring poles together and apart, and watch whether they attract or repel.
- Attraction is not proof: Two magnets can attract or repel, but a magnet also attracts plain iron, so only repulsion is a true test.
- The rule: like poles repel, unlike poles attract.
- Induced magnetism: a magnet attracts any unmagnetised magnetic material, so attraction proves nothing on its own.
- The test: if two objects repel, both must be magnets, because only like poles push apart.
One picture every idea returns to
Every magnet has a north pole and a south pole. Like poles repel and unlike poles attract, and the force acts at a distance without contact. Repulsion is the only sure test that a material is itself a magnet.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Like repels, unlike attracts.. Bring two magnets together and they either snap shut or push your hands apart, depending on which ends you offer. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Feel the force between poles | Bring poles together and apart, and watch whether they attract or repel. Project tab 2 of the lab (Poles and forces) and let a student drive it while the class predicts. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Attraction is not proof | Two magnets can attract or repel, but a magnet also attracts plain iron, so only repulsion is a true test. | Mix-Pair-Share |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 15 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Attraction is not proof, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Mix-Pair-Share
Students mix around the room until you call pair; they pair with the nearest classmate, discuss the prompt, then mix again. Three prompts of rising difficulty, three different partners.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| Repulsion is the only certain test that a material is magnetised. | Attraction is not enough, because a magnet also attracts an unmagnetised magnetic material such as iron. |
Magnetic poles and forces: worksheet
6 questions, 15 marks. Written in the style of the papers; no past paper question is reproduced.
State what happens when each of the following pairs of poles is brought close together.
(a) A north pole and a north pole.
(b) A north pole and a south pole.
Name two metals that are attracted to a magnet, and state one common metal that is not.
An unmagnetised iron nail is brought near the north pole of a strong magnet, and the nail is attracted to it.
(a) Name the effect that lets the nail be attracted even though it is unmagnetised.
(b) State which pole is induced in the end of the nail nearest the magnet, and explain why.
A bar is brought near a known magnet. When one pole of the magnet is offered, the bar is pushed away.
(a) State whether the bar is definitely a magnet.
(b) Explain your answer.
Two identical-looking steel bars, P and Q, are both attracted to each other whichever way round they are held. A student claims this proves both are magnets.
State whether the student is correct, and explain what the observation does and does not tell you.
Two magnets are held with their north poles facing each other. Describe how the force between them changes as they are pushed closer together, and name the type of force.
Answer key and marking notes
(a) They repel (push apart). ✓
(b) They attract (pull together). ✓
like poles repel, unlike poles attract
- Attracted: any two of iron, steel, cobalt, nickel. ✓
- Not attracted: copper (or aluminium, brass, gold). ✓
(a) Induced magnetism. ✓
(b) A south pole is induced in the near end. ✓
The induced pole is opposite to the approaching north pole, so unlike poles face each other and the nail is attracted. ✓
(a) Yes, it is definitely a magnet. ✓
(b) The bar was repelled, and only like poles repel each other. ✓
An unmagnetised material can only be attracted, never repelled, so repulsion proves the bar has its own pole. ✓
- The student is not correct. ✓
- Attraction every way round is also what happens if only one bar is a magnet and the other is unmagnetised steel, by induced magnetism. ✓
- To prove both are magnets, the student must find an orientation in which they repel. ✓
- The poles are alike, so the force is a repulsion that gets stronger as they get closer. ✓
- It is a non-contact force (it acts without the magnets touching). ✓
2 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
The north pole of one bar magnet is brought close to the north pole of another. What happens?
- AThey repel each other.
- BThey attract each other.
- CNothing happens.
- DThey attract only if one is made of steel.
An unmagnetised steel paper clip is attracted to either pole of a magnet. Why does the same paper clip move toward both the north and the south pole?
- AThe magnet induces magnetism in the clip, so the clip always gains an opposite pole facing the magnet.
- BSteel is repelled by both poles equally.
- CThe paper clip already has a fixed north and south pole.
- DPaper clips are slightly charged.
Quiz key
Like poles repel, so two north poles push apart. Unlike poles (N and S) would attract. The force acts between the magnets without needing contact.
The magnet induces magnetism in the steel: the end nearest the magnet becomes the opposite pole, so attraction always results, whichever pole is presented. Attraction works for either pole, while only another magnet can show repulsion.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.